Illumination optical unit for projection lithography and hollow waveguide component therefor

Abstract

An illumination optical unit for projection lithography guides illumination light toward an object field and has a mirror array including a multiplicity of individual mirrors which are tiltable independently. A condenser optical unit transfers an arrangement plane of the mirror array into a pupil plane of the illumination optical unit. An optical hollow waveguide component of the illumination optical unit is upstream of the mirror array in the beam path of the illumination light and homogenizes and stabilizes an illumination light beam incident on the mirror array. An input coupling optical unit is upstream of the hollow waveguide component and couples an incident illumination light beam into the hollow waveguide component. A relay optical unit images a beam exit surface of the hollow waveguide component onto the mirror array. The illumination optical unit is insensitive to light source instabilities.

The invention claimed is: 
     
       1. An illumination optical unit configured to guide illumination light along a path toward an object field, the illumination optical unit comprising:
 an input coupling optical unit; 
 a hollow waveguide component downstream of the input coupling optical unit along the path; 
 a random phase element upstream of the input coupling optical unit along the path; 
 a relay optical unit downstream of the hollow waveguide component along the path; and
 a mirror array downstream of the relay optical unit along the path, 
 wherein:
 the mirror array comprises a multiplicity of individual mirrors which are tiltable independently of each other; 
 the input coupling optical unit is configured to couple a beam of the illumination light into the hollow waveguide component; 
 the relay optical unit is configured to image a beam exit surface of the hollow waveguide component onto the mirror array; and 
 the hollow optical waveguide component is configured to homogenize and stabilize a beam of the illumination light incident on the mirror array. 
 
 
 
     
     
       2. The illumination optical unit of  claim 1 , wherein the illumination optical unit is configured so that an internal reflection angle of the illumination light in the hollow waveguide component is greater than 85°. 
     
     
       3. The illumination optical unit of  claim 2 , wherein the hollow waveguide component has a ratio of waveguide length to waveguide cross section of at least 100. 
     
     
       4. The illumination optical unit of  claim 3 , wherein the hollow waveguide component has a cavity with a rectangular waveguide cross section. 
     
     
       5. The illumination optical unit of  claim 4 , wherein the hollow waveguide component comprises at least two separate component parts combined so that each component part delimits at least one internal reflection surface of the hollow waveguide component. 
     
     
       6. The illumination optical unit of  claim 1 , wherein the hollow waveguide component has a ratio of waveguide length to waveguide cross section of at least 100. 
     
     
       7. The illumination optical unit of  claim 1 , wherein the hollow waveguide component has a cavity with a rectangular waveguide cross section. 
     
     
       8. The illumination optical unit of  claim 1 , wherein the hollow waveguide component comprises at least two separate component parts combined so that each component part delimits at least one internal reflection surface of the hollow waveguide component. 
     
     
       9. The illumination optical unit of  claim 8 , wherein the hollow waveguide component comprises four separate component parts combined so that each component part delimits at least one internal reflection surface of the hollow waveguide component. 
     
     
       10. The illumination optical unit of  claim 9 , wherein the hollow waveguide component comprises four at least partly reflectively coated mirror parallelepipeds. 
     
     
       11. The illumination optical unit of  claim 1 , wherein the hollow waveguide component comprises at least partly reflectively coated mirror parallelepipeds. 
     
     
       12. The illumination optical unit of  claim 1 , wherein the relay optical unit has a magnifying imaging scale of at least 10. 
     
     
       13. The illumination optical unit of  claim 1 , wherein the relay optical unit comprises more than one lens element. 
     
     
       14. The illumination optical unit of  claim 1 , further comprising a plurality of actuators configured to tilt the individual mirrors. 
     
     
       15. An optical system, comprising:
 an illumination optical unit according to  claim 1 ; and 
 a projection optical unit configured to image the object field into an image field in an image plane. 
 
     
     
       16. An illumination system, comprising:
 an illumination optical unit according to  claim 1 ; and 
 a light source configured to generate generating the illumination light. 
 
     
     
       17. An apparatus, comprising:
 an optical system, comprising:
 an illumination optical unit according to  claim 1 ; and 
 a projection optical unit configured to image the object field into an image field in an image plane; and 
 
 a light source configured to generate generating the illumination light, 
 wherein the apparatus is a projection exposure apparatus. 
 
     
     
       18. A method of using a projection exposure apparatus comprising an illumination optical unit and a projection optical unit, the method comprising:
 using the illumination optical unit to illuminate at least some structures of a reticle in an object plane of the projection exposure apparatus; and 
 using the projection optical unit to project at least a portion of the illuminated structures of the reticle onto a light-sensitive material in an image plane of the projection exposure apparatus, 
 wherein the illumination optical unit comprises an illumination optical unit according to  claim 1 . 
 
     
     
       19. An illumination optical unit configured to guide illumination light along a path toward an object field, the illumination optical unit comprising:
 an input coupling optical unit; 
 a hollow waveguide component; 
 a random phase element upstream of the input coupling optical unit along the path; 
 a relay optical unit; and 
 a mirror array, 
 wherein:
 the mirror array comprises a multiplicity of mirrors; 
 the input coupling optical unit is configured to couple a beam of the illumination light into the hollow waveguide component; 
 the relay optical unit is configured to image a beam exit surface of the hollow waveguide component onto the mirror array; and 
 the hollow optical waveguide component is configured to homogenize and stabilize a beam of the illumination light incident on the mirror array. 
 
 
     
     
       20. An illumination optical unit configured to guide illumination light along a path toward an object field, the illumination optical unit comprising:
 an input coupling optical unit; 
 a hollow waveguide component; 
 a random phase element upstream of the input coupling unit along the path; and 
 a mirror array, 
 wherein:
 the mirror array comprises a multiplicity of mirrors; 
 the input coupling optical unit is configured to couple a beam of the illumination light into the hollow waveguide component; and
 the hollow optical waveguide component is configured to homogenize and stabilize a beam of the illumination light incident on the mirror array. 
 
 
 
     
     
       21. The illumination optical unit of  claim 1 , wherein:
 the random phase element comprises a plurality of each regions; 
 each region comprises a plane parallel entrance surface, a plane parallel exit surface, and a thickness between its plane parallel entrance surface and its plane parallel exit surface; and 
 the thickness of different regions is different so that the transition between different regions is stepped. 
 
     
     
       22. The illumination optical unit of  claim 20 , wherein:
 the random phase element comprises a plurality of each regions; 
 each region comprises a plane parallel entrance surface, a plane parallel exit surface, and a thickness between its plane parallel entrance surface and its plane parallel exit surface; and 
 the thickness of different regions is different so that the transition between different regions is stepped. 
 
     
     
       23. The illumination optical unit of  claim 19 , wherein:
 the random phase element comprises a plurality of each regions; 
 each region comprises a plane parallel entrance surface, a plane parallel exit surface, and a thickness between its plane parallel entrance surface and its plane parallel exit surface; and 
 the thickness of different regions is different so that the transition between different regions is stepped.